Constructing a subterranean well for producing substantially water, e.g. from solution mined or water cut hydrocarbon wells, or for producing substantially hydrocarbons, requires capital investment with an expectation of a return on capital repaid over the life of the well, followed by the permanent abandonment of all or part of the well to delay further cost, once storage or producing zones have reached the end of their economic life or the well's structural integrity becomes an issue. For the hydrocarbon extraction industry, the producing life of a well is, typically, designed for 5 to 20 years of production. However, conventional practice is primarily to extend well life as long as possible, even after exceeding its original design life, and, despite any marginal economic losses incurred, to push the cost of final abandonment into the future. For the underground storage industry, wells may be designed for a 50 year life span, but over time storage wells may also encounter integrity issues that require intervention, maintenance or abandonment.
Embodiments of the present invention are usable to delay abandonment by placing well barrier element members to intervene in or maintain a well's structural integrity to allow additional marginal production or storage operations until final cessation of production or storage operations. Embodiments are further usable to permanently abandon all or part of produced subterranean or underground storage wells.
As the cost of placing acceptable abandonment barriers to permanently isolate subterranean pressurized liquids and gases comprises an investment without a return on capital, the financially minded are continually seeking to reduce the net present cost of abandonment by either delaying it through marginal production enhancement or by minimising expenses associated with abandoning the lower portion of a well, sometimes referred to as suspension until final abandonment of a well.
Embodiments of the present invention are usable with rig-less intervention operations to minimize the cost of marginal production enhancement and the abandonment of a portion of a well to suspend the well until a final abandonment campaign is used to further minimize costs, potentially using rig-less embodiments.
The present invention relates, generally, to rig-less systems and methods usable to install well barrier element isolations to delay or perform subterranean well abandonment operations on at least a portion of a substantially water or substantially hydrocarbon well. This allows and/or provides for the production or storage from a different portion of the well until the well has reached the end of its life and is ready for final rig-less abandonment, by using the installed conduits that are engaged to the wellhead, to place apparatuses or settable fluid mixtures at selected depths to isolate at least a portion of the well using rig-less operable annulus engagable members and methods of the present invention.
Various embodiments of the present invention may include the use of, or be usable with, other inventions of the present inventor, including the inventions disclosed in the United Kingdom Patent GB2471760B, entitled “Apparatus And Methods For Sealing Subterranean Borehole And Performing Other Cable Downhole Rotary Operations” published 1 Feb. 2012; U.S. patent application Ser. No. 12/803,775, entitled “Through Tubing Cable Rotary System” filed on Jul. 6, 2010 and published under US2011/0000668 A1 on Jan. 6, 2011; PCT Patent Application Serial Number GB2010/051108, entitled “Apparatus And Methods For Sealing Subterranean Borehole And Performing Other Cable Downhole Rotary Operations” filed Jul. 5, 2010 and published under WO2011/004183A2 on Jan. 31, 2011; and PCT Patent Application Serial Number PCT/US2011/000377, entitled “Manifold String For Selectively Controlling Flowing Fluid Streams Of Varying Velocities In Wells From A Single Main Bore” filed Mar. 1, 2011 and published under WO2011/119198 A1 on Sep. 29, 2011, all of which are incorporated herein in their entirety by reference.
The present invention significantly improves upon prior art with methods and apparatus embodiments for forming and using four (4) dimensional geologic time well barrier elements necessary for the practice of cap rock restoration, wherein the provision of a operable space for logging the cement bonding of a three (3) dimensional space prior to placing and supporting at least one cement equivalent barrier member within said operable space, using at least one annulus engagable member to access at least one annulus from an innermost passageway, by displacing at least one portion of a wall of at least one conduit surrounding the innermost passageway to provide said operable space, bridge across said operable space, and place said at least one cement equivalent well barrier member through said operable space to form at least one geologic time-frame space, which can be usable to fluidly isolate at least one portion of a subterranean well without removing installed conduits and associated debris from below one or more subterranean depths, to provide or enable cap rock restoration above a producible zone.
For example, Patent GB2471760B of the present inventor is usable to form a four (4) dimensional space when the elements of a geologic time frame space happen to be present, for example, when an immovable production packer does not block an annular passageway. The present invention provides significant improvements by providing the elements of a geologic time frame in instances where said elements may otherwise be unachievable without the use of a drilling rig. The present invention's methods and apparatuses are usable to, for example, place and/or jar cement equivalent sealing material about the annulus blockage, such as a production packer, to increase the probability of successfully forming a geologic fourth dimensional space at the specific depth defined by the cap rock, which previously contained a producible zone before it was penetrated by the well. Consequently, the spectrum of wells available for rig-less abandonment increases significantly by enabling or providing for the re-sealing of said cap rock at said specific depth according to conventional industry practices for sealing a well over the fourth dimension of geologic time.
Similarly, the present invention provides significant improvements upon prior art, for example WO2004/016901 A1 entitled “Well Abandonment Apparatus,” which is silent to industry cap rock replacement practice and lower cost rig-less cable conveyable practices, and teaches the use of higher cost drillpipe and coiled tubing conveyance and circulation methods, using electrical and hydraulic umbilical lines for power and control. In contrast, the present invention can use the circulatable fluid column, within the plurality of passageways formed by in-place tubing and casing, to operate an annulus engagable member and form and/or use a four (4) dimensional operable space, which can be consistent with the practice of cap rock restoration at the geologic dictated depth necessary for providing or enabling said cap rock restoration over a geologic time frame.
The present invention provides a rig-less well annuli access and abandonment system of methods and members usable to solve the complex set of problems that have forced industry to use expensive, over-specified, drilling rigs and/or deployed pipe circulation to meet minimum published well suspension, sidetracking and abandonment best practice and standards. Conventional rig-less technology generally uses, for example (e.g.), perforating guns, abrasive cutters and severing explosives to crudely engage annuli or complex and relatively large and still expensive rig-less coiled tubing or pipe handling arrangements unsuitable for instances constrained by minimum space and infrastructure, such as normally unmanned minimum remote onshore wells and offshore facilities.
The present invention provides cable compatible embodiments, usable with slick line and braided coiled wire strings to provide selectively controllable access to all well annuli to: i) adequately clean the annuli to provide a wettable surface for proper bonding of cement and other suitable permanent well barrier elements, ii) provide logging access to confirm the presence of primary cement behind well casings, iii) provide stand-off between well conduits to ensure that conduits are embedded in cement and/or have cement inside and outside of the metal conduits to prevent corrosion, iv) remove potential leak paths such as control lines and cables from annuli, and vi) place well barrier elements across from strong impermeable formations to meet published industry best practices for permanent abandonment, where no comprehensive conventional rig-less abandonment system is available for minimum facilities with limited space and resources, e.g. power, and larger facilities where the cost of numerous complex system rig-ups and rig-downs over a plurality of wells is cost prohibitive.
The methods and systems of the present invention are usable in various combinations to provide, in whole, a rig-less well suspension, side-tracking and abandonment system to meet industry best practices described in various publications, including NORSOK D-010 revision 3, August 2004, which define the requirements of conventional well barrier elements used to form a plurality of pressure bearing envelops that resist subterranean pressurized liquids and gasses.
The methods and apparatus of the present invention differ from the conventional hydrocarbon and storage industry practices and apparatuses, which are designed for a significant life cycle, because the present embodiments are usable with a more economic means of placing a permanent well barrier element. For example, where a conventional tubing patch is designed to repair breached tubing for a significant period of production, various embodiments of the present invention are usable to provide temporary and/or partial fluid pressure circulating capabilities to place a permanent cement plug, because the extra expenditure to repair the breached tubing is unnecessary, given that the well is being abandoned. Furthermore, the present invention is usable to increase the number of wells, where lower cost rig-less slickline operations are usable to place permanent well barrier elements, like cement, as opposed to the conventional practice of using an extremely expensive and over specified drilling rig to perform work on an asset that has no further value.
The present invention can be usable with rigs or conventional rig-less arrangements, such as those described in U.S. Pat. No. 7,921,918B2, published the 12th of April 2011, incorporated herein in its entirety by reference to provide reference to a rig-less conduit handling system. However, the present invention can be further usable to minimize the required operational footprint and resources, because the systems and apparatus of the present invention may be used with, but do not require, pipe handling arrangements and are operable with tension of a coiled wireline or coiled tubing string and pumping arrangements, or optionally, with electric line, through the wellhead using the well's circulatable fluid column.
Various methods and fluid and apparatus member embodiments of the present invention's rig-less suspension, sidetracking and abandonment systems can be combinable with conventional rig-less operable methods and apparatuses when placing well barrier elements and forming branching passageways, from the innermost passageway, to be used for accessing annuli and producible zones of a well and/or forming new well barrier elements, which can be rig-lessly placeable with jointed conduits, coiled strings and/or a well's circulatable fluid column.
Pumpable members of the systems of the present invention represent significant improvement over the teachings of EP0933414A1, published 4 Aug. 1999, and GB2429725A, published 7 Mar. 2007 which describe swellable gravel packs; US 200310144374A1, published 31 Jul. 2003, and EP1614669A1, published 29 Jun. 2005, which describe organophillic clay and cement mixtures; all of which are included herein in their entirety by reference. Where conventional practice focuses on water production isolation, with swellable and reservoir isolation with clay and cement, the present invention provides methods for mixing gradated hard particles that can be combinable with swellable particles and clay based cement to form an annuli bridging matrix or pseudo packer within well annuli, forming well barriers and/or supporting placement of a permanent barrier, e.g., neat cement. The present invention further improves conventional or existing practices for rig-less abandonment by incorporating reagent mixing methods from the drilling industry, commonly referred to as gunk, usable to temporarily seal leaks downhole. The present invention's combination of gradated hard and swellable particles mixed with organophillic clay, oils and cement provide a means for isolating well annuli during rig-less operations and providing permanent barriers within selected portions of a well.
Other existing methods and systems, for example, EP0933414A1 and GB2429725A describe swellable particle packs used in water shut-off and gravel packs, while US 2003/0144374A1 and EP1614669A1 describe an organophillic clay cement mixture usable for sealing producible hydrocarbon formations, historically comparable to drilling practitioner's use of “gunk” for closing fractured formations during drilling operations. Conventional packing methods are silent as to the present embodiments comprising hard gradated particles mixed with gradated swellable particles and clay mixtures to form a fluid deployable hard pressure bearing matrix or pseudo packer within an annulus, as specified within the present invention. Thus, the present invention provides significant improvement and benefit to rig-less intervention and abandonment practitioners, with the use of rheological controllable fluid members comprising, for example, hard size specific particles mixed with size specific gradated, swellable, particle packing mixes, wherein the pore spaces are filled with a clay-based gunk or clay-based cement to form a pressure-bearing matrix. The pressure bearing capacity of rheological controllable fluids of the present invention are further increasable with hydraulic packing methods and members, usable with intermixable gelatinous gunk or cement pumpable gradated swellable particle mixes, to form stress and pressure bearing matrices with the swellable particles, and harder intermediate gradations of particle sizes mixed with the low gravity solids and particle sizes of a clay-based gunk or cement to seal the pores spaces between the packed particles and a wall of a well, e.g. a conduit, permeable conduit and/or strata wall, such that a pseudo packer may be formed in annuli of a well for well abandonment, suspension and side tracking purposes. This pseudo packer is compatible with the setting nature of cement or oil-based gunk to provide support for sealing materials, forming an indefinite pressure bearing bridging of, e.g., cement across the walls and circumference of well annuli during the rig-less abandonment and/or temporary suspension of subterranean wells. Additionally, the present invention represents a significant improvement over conventional clay cement mixes, with method embodiments for segregating deployment of reagents of chemically reactive fluid mixes to control mixing and chemical gelling, at the point where a well barrier element is needed, wherein further chemical reaction of swellable material to, e.g., hydrocarbons or water is also possible at said point.
Boring and expandable conduit placement of the present invention represents significant improvement over such teachings as those disclosed in U.S. Patent Application 2005/0252688, published Nov. 17, 2005, and U.S. Patent Application 2004/0069487A1, published 15 Apr. 2004, which describe micro bore drilling and logging; and WO 2009/152532A1, published 17 Dec. 2009, which describes drilling a hole in a conduit and placing a sealable material within an annulus. The present invention improves upon such conventional practice by providing a plurality of sizes and placement means through which well barrier elements and logging tools may be placed to confirm primary cementation behind casing to meet published minimum industry requirements, whereas similar conventional coiled wire string compatible methods or apparatuses are not available for the economic abandonment of a well.
Axial screw and/or tractor embodiments of the present invention provide more robust combinable pipe destruction and conveyance means for shredding and milling of well conduits, which do not require computer control as described in the teachings of U.S. Pat. No. 6,868,906B1, published 22 Mar. 2005. With regard to complex computer systems, Greenfield hydrocarbon production has significant value, and the associated economics of using computer controlled systems is significant during construction of a well; however, abandoned wells have no future value with well conduits of no further use after deconstruction of a well, generally termed as abandonment. Hence, the economics of abandonment are significantly different and require different tooling. The present invention provides significant improvements in the field of low cost rig-less intervention by providing a system of methods and apparatus to meet the lower cost needs of rig-less abandonment, which can be usable for suspension and side-tracking of marginal producible zones of a well that may not have warranted completion during initial well construction and/or do not warrant the use of a drilling rig or expensive computer operated systems, but are usable to provide marginal revenue to offset the cost of delaying final abandonment.
U.S. Patent Application 2005/0252688 describes methods for single micro-bores through strata immediately adjacent to cemented casings to place expandable sand screens for a producible formation. However, this reference is silent to, and is unsuitable for, simultaneously placing a plurality of bores and/or selectively accessing said bores with subsequent tools, such as conventional logging tools. Further, this conventional method does not teach the placing of integral passageways through annuli, as described by the present invention. While U.S. Patent Application 2004/0069487 A1 describes methods for providing strata measurements and fluid traces within a micro bore, it does not teach the provision of sufficient diameter, angular offset or selective bore hole re-entry. Further, the invention taught in WO2009/152532A1 is usable to make holes or cuts within an innermost conduit to access a single annulus and place a well barrier element settable material in the annulus; however, this reference does not teach, nor is it usable to, access a plurality of annuli and/or placement of measurement devices needed for cap rock restoration using well barrier element members, such as settable sealing materials. Also, WO2009/152532A1 does not teach the provision of a conduit for production or storage from a different part of the well to delay final abandonment with marginal production. Conversely, the present invention teaches a plurality of bores and expandable conduits that are not restricted to micro-boreholes and are usable for fluid communication, placement of conventional logging apparatuses and other devices, prior to placing cement according the published industry guidelines. Thus, the present invention provides significant improvements over conventional technology by allowing for more and larger bore holes and conduit sizes through the innermost bore of a well. This then allows well operators to selectively guide, for example, electric motors and higher torque coiled string fluid motors to selectively place larger boring bits and selectively access a plurality of larger bit-carried-expandable-conduits, usable with higher flow rates, to fluidly communicate through annuli, which are isolatable from the carried expandable conduit passageway to, e.g., access producible zones, place devices, well barrier elements and/or rheological controllable fluid members.
The low torque centrifugally deployed disposable coiled cable string compatible milling embodiments of the present invention represent significant improvement over the existing technology, such as those of U.S. Pat. No. 5,101,895A1, published 7 Apr. 1997, and WO2009/152532A1, published 17 Dec. 2009. The present invention provides a significant improvement for rig-less, low-cost milling with balanced ball joint mills deployable with centrifugal forces of rotation and arranges so as to reduce torque and be disposable downhole if the mill becomes stuck during use.
One of the primary objectives of rig-less abandonment of any portion of a well is its destruction at the lowest possible cost, wherein the present invention is comprised of low cost, simple and robust methods and members that can be more akin to using a sledge hammer than using the conventional computer controlled teachings of U.S. Pat. No. 6,868,906 B1, involving complex computer controlled tractor conveyance of drilling assemblies for well services and deployable on wireline or umbilicals, only. The operational benefits of the present invention are numerous and significant, needing only fluid circulation, an electricity supply and/or line tension for operation, versus complex operations requiring computer control, wherein the simple operations of the present invention are generally easier to support and less expensive. Additionally, if an assembly becomes stuck downhole, the value of retrieving the complex closed loop system operated apparatuses and tractors are significant, given the construction cost of complex apparatuses, thus limiting their utility for risk of loss within operations like abandonment where the well is a liability without future value. Methods and members of the present invention are rig-lessly operable, with cable tension and the pressures of a circulated fluid column to drive a fluid motor or an electrical conductor to operate an electrical motor and/or disposable tractor, using the low cost disposable motor's reactive torque to drive the pushing or pulling of various disposable rotating or non-rotating apparatuses to penetrate walls within a well that is incapable of providing future return on investment. The hazards of destructing said well, e.g. the violent jarring, milling, shredding and tractor cutting wheel destruction of steel conduits, by crushing, cutting and rotating equipment suspended from a non-rotatable cable, represents a significant risk of becoming stuck downhole and/or breaking the cable. The present invention provides significant benefit over more complex systems, e.g. U.S. Pat. No. 6,868,906B1, U.S. Patent Application 2005/0252688, U.S. Patent Application 2004/0069487A1 and WO2009/152532A1, because it requires a less complex system designed for operating under the high tension load of, e.g., a capstan cable pulling unit, wherein members may be disposed of downhole, if necessary, to avoid the more costly operation of more complex systems, with an intrinsic re-usable value justifying said complex system's retrieval.
Additionally, conventional devices, such as those described in WO 2009/152532 A1, are generally unsuited for use with cable operations because erratic rotation of its unbalanced milling arm will occur when the conduits being milled shift, thus placing unacceptable tensional loads on a high-torque downhole motor, potentially causing damage or sticking and slipping issues for its milling assembly, which are generally unsuitable for cable operations where low torque and balanced rotation are required to prevent fouling of the cable. While U.S. Pat. No. 5,101,895A1 provides a balanced cutting and/or milling blade arrangement, the milling blades are driven by supplied torque and constrained within a rigid deployment arrangement that does not automatically adjust to balance rotation, limit torque and prevent vibration, that is unacceptable for a cable deployed milling tool. Conversely, rotary cable tool milling embodiments of the present invention comprise balanced deployment mills that intrinsically adjust to conduit eccentricity with ball joints and rotating cutting structures, which are suitable for lower torque motors on coiled string applications to prevent erratic rotation with the centrifugal forces of rotation adjusting deployment of the mills if conduits shift.
The present invention provides significant improvements over the teachings of U.S. Pat. No. 5,957,195, published 28 Sep. 1999 describing an expandable tubing patch usable to repair a leak in production tubing. The present invention provides a swellable, expandable mesh-membrane fluid conduit that can be usable to place cement and/or rheological controllable fluid members in any annulus and/or to choke fluid communication between the innermost passageway and one or more of the annuli. Thus, the present invention provides a significant improvement over conventional expanded tubing patches in the field of rig-less abandonment, due to the high probability that the condition of the tubing that caused the first breach is the result of age, corrosion and/or wear that will lead to further breaches or tubing collapse, which cannot be repaired with a single patch. In contrast, the present invention can include the ability for burst or collapse prevention as well as an ability to repair the tubing, due to the permeability of the mesh, which can provide pressure relief to prevent burst or collapse of the tubing, while placing and allowing a cement to harden, and whereby the mesh can allow removal of free water associated with cement setting, unlike a solid conventional tubing patch. Furthermore, an expanded mesh conduit can be placed through annuli of a well, and is usable to urge heavier viscous fluids, e.g. cement, through or about the mesh conduit, wherein the pore spaces of the mesh can provide a natural pressure relief system, which may allow limited leakage to prevent burst or collapse of a fluid conduit when fluids of differing densities exist inside and outside the conduit, unlike conventional expandable solid tubing technology. Additionally, the present invention represents a significant improvement over conventional expandable sand screens that are designed for preventing sand production, by introducing swellable sleeves or gradated packable and swellable particles to an expandable mesh screen conduit, which provide the benefits of pressure relief to prevent conduit collapse while urging a majority of fluids communicated through the conduit to a selected location.
Various method and apparatus embodiments of the present invention's system of members are usable to form an enlarged passageway, including the milling and shredding of well conduits and equipment and/or compression or compaction of installed well conduits and equipment to, e.g., further form or enlarge passageways for placement of a permanent well barrier element. Other various embodiments comprise small drilling and casing assemblies, usable to place small diameter boreholes and/or expandable casings, expandable seals or swellable materials within bores and annuli of a well, to form pressure bearing passageways usable to place, e.g., logging equipment to determine any necessary remedial action within a bore or annuli of a well. The present invention is therefore usable for marginal production enhancement or underground storage well integrity repairs to provide further revenue and to reduce overall net present cost of well abandonment by delaying it, wherein the present invention is also usable for final abandonment of the subterranean portions of a well.
Well abandonment represents actions taken to ensure the permanent isolation of subterranean pressurized fluids from surface and/or other lower pressured exposed permeable zones, e.g. water tables, for various portions of a well where re-entry is not required, and wherein the portions, being selectively used and/or abandoned, require permanent fluid isolation, at depths specified by pressures within the strata, and the pressure bearing ability of the overlying strata to isolate lower strata fluid pressures from the surface or other upper permeable zones. Subterranean pressurized permeable zones comprising strata formations accessed by a well having a possibility of fluid movement when a pressure differential exists, generally, must be isolated to prevent pollution of other subterranean horizons, such as water tables, or surface and ocean environments.
Various embodiments of the present invention are usable within a pressure controlled working envelope, using coiled strings, lubricators, grease heads or other conventional pressure control equipment, engaged to the upper end of a wellhead and valve tree to intervene within the passageways and annuli of a subterranean well extending downward from the wellhead to permanently isolate subterranean pressurized fluids accessed by the passageways without the risk and cost of placing dense kill weight fluids in the well and breaking through surface pressure barriers, thus exposing personnel and the environment to a higher potential for uncontrolled fluid flow if the dense fluid column killing subterranean pressures is lost.
Performing well intervention and abandonment operations within a pressure contained environment is required for rig-less operations in a subsea environment where risers and lubricators must be engaged to the upper end of a subsea valve tree to remove plugs, for accessing the innermost well bore. However, access to annuli within a subsea well is limited, with most wells opening the innermost annulus to the production stream during initial thermal expansion after which subsea annuli are closed. Many subsea configurations also provide fluid access to the innermost annulus through a manifold placed on the subsea valve tree, which may also be engaged with the supporting conduit pipelines, such as a methanol line. The present invention is usable from a boat and lubricator arrangements, within a pressure controlled environment, e.g. a subsea lubricator and BOP, to rig-lessly access and abandon a well without a he need for a riser from mudline to or above sea-level.
Permanent abandonment, generally, is considered to be the placement of a series of permanent barriers, often referred to as plugging and abandoning, in all or part of a well with the intention of never using or re-entering the abandoned portion. Permanent well barriers are, generally, considered well barrier envelopes comprising a series of well barrier elements that individually or in combination create an encompassing seal, which has the permanent or eternal characteristic of isolating deeper subterranean pressures from polluting shallower formations, e.g. ground water permeable zones, and/or above ground or ocean environments. Various publications, including Oil and Gas UK Issue 9, January 2009 Guidelines for Suspension and Abandonment of Wells, define conventional best practice for permanent abandonment of a well and the associated acceptable well barrier elements used to form a plurality of pressure bearing envelops, resisting subterranean pressurized liquids and gasses over geologic time.
Presently, there are no existing comprehensive systems for abandoning wells, other than the use of an over-specified and expensive drilling rig. The present invention provides an important and significant solution by specifying methods and apparatuses to rig-lessly suspend, sidetrack and abandon onshore and offshore, surface and subsea, substantially hydrocarbon and substantially water wells, which also complies with the published conventional best practices for placement of industry acceptable permanent abandonment well barrier elements.
The cost of permanent abandonment can be expressed as a function of the time span required and the quantity and type of equipment needed to place permanent barriers to contain subterranean fluid pressures for an indefinite period of time. The cost of abandonment is generally higher when using a drilling specification rig, capable of constructing a well, with large capacity hoisting, pumping and conduit handling systems requiring a significant amount of supporting equipment and personnel to operate. Conversely, the cost of abandonment is generally significantly lower when operating what are generally termed as “rig-less” systems, with significantly less support equipment and personnel operating lower capacity hoisting, pumping and conduit handling systems.
Embodiments of the present invention are generally usable to meet published industry minimum requirements and best practices for placement of permanent barriers using rig-less intervention and abandonment methods.
Drilling specification rigs are, generally, used to deconstruct a well by cutting and hoisting large and/or long strings of conduits from a well and potentially mill casings to place unobstructed cement plugs within the bores from which the conduits were removed. Conventional hazards exist, particularly when equipment within a well must be removed to place acceptable eternal barriers, wherein the equipment may be coated with low specific activity (LSA) scale or normally occurring radioactive material (NORM) deposits, which accumulated over the well's productive life. The rig-less abandonment embodiments of the present invention are usable to protect the environment and personnel from these hazards, which, if achievable in existing practices, would add additional costs and/or reduce the efficiency of the abandonment practice. The rig-less abandonment embodiments of the present invention provide acceptable methods and systems usable to leave the contaminated well equipment within the strata.
Embodiments of the present invention are usable with installed well apparatuses to avoid the need for completion equipment removal and exposure of personnel and the environment to various hazardous materials, which may have accumulated on the equipment over time.
In instances where insufficient cement exists behind casing and production equipment has been removed, a drilling rig may be conventionally required to mill the casing, so as to place a cement plug across the unobstructed strata bore. The resources and associated costs required for casing milling operations may often be equivalent to the original conventional cost of constructing the well.
Various embodiments of the present invention are usable to access annuli so as to measure the presence of cement behind casing, or the lack thereof, while other various embodiments are usable to shred production conduits and mill casing to provide an unobstructed space for placement of cement across a bore.
Operating a drilling rig requires a significant amount of space surrounding the wellhead of the well being constructed or deconstructed for the placement and operation of large capacity hoisting, pumping and conduit handling systems, regardless of whether the work occurs onshore or offshore. Drilling rigs are, generally, the primary controllable expensive driving return on capital and offshore drilling specification rigs are, generally, significantly more expensive than onshore drilling rigs, because they comprise living habitats capable of supporting a significant number of people, often exceeding a hundred persons, within a potentially hazardous environment. While the requirements for coiled tubing well operations are significantly less than those for a drilling rig, they are considerably greater than those of a wireline operation comprising electric line or slickline intervention.
The present invention is usable to provide smaller rig-less operational footprints, similar to electric line and slickline operations, usable, e.g. on small normally unmanned platforms, with methods and apparatus requiring a minimum of resources and associated space to perform necessary suspension, side-tracking and, ultimately, abandonment operations.
Large hoisting capacity rigs usable for the removal of downhole equipment are not generally required, provided that annuli can be accessed and permanent isolations can be placed within annuli. Generally, rig-less abandonment operations use through tubing or through conduit operations to minimise equipment and personnel requirements, using the installed completion and casing strings to circulate cement, and, ultimately, leave equipment downhole.
Providing annulus control and permanent isolation barriers with rig-less operations is challenging with no universally accepted conventional rig-less means of both verifying and placing permanent barriers within annuli, as required by the published industry best practices, because of the many potential leak paths that exist when completion equipment is left within a well, wherein conventional logging can only occur after the completion equipment has been removed. For example, leaving cables and control lines downhole within a cement barrier can represent a significant leak path because capillary or frictional forces may prevent viscous cement from entering the small diameter of a control line or sheath of a cable. Additionally, while records of originally installed primary cementation may exist, over time the primary cementation bond may have failed from the pressures and thermal cycling of the casings during production, and a leak path may exist between casings and the strata rendering properly placed conventional rig-less abandonments ineffective.
Additionally, when well completion tubulars or conduits and completion equipment are left downhole during through conventional tubing rig-less well abandonment, leak paths may form around the installed apparatuses if they are not offset from other equipment so as to be embedded in, e.g., cement, including verification of the position and placement of the permanent barriers inside bores and annuli of a well to determine if further remedial action is required.
Various embodiments of the present invention are usable to compress severed well equipment within a surrounding bore to remove obstructions and potential leak paths while providing space for logging behind casing, to determine whether an acceptable cement bond exists.
The main characteristics that a permanent barrier must have to prevent flow of pressured fluids through the barrier are: i) long term isolation integrity that ii) bonds to completion equipment and iii) does not deteriorate over time or iv) shrink, thus allowing flow around the barrier, which must be of a v) ductile or non-brittle nature to accommodate mechanical loads and changes in the pressure and temperature regime, wherein the ductile or non-brittle material must also vi) resist ingress of downhole fluids and/or gases, such as hydrocarbon gas, CO2 and H2S into or through its mass. While cement is currently the primary oil and gas industry material used for permanent well barriers, other suitable materials may also be usable, provided they meet these necessary conventional requirements.
Embodiments of the present invention are usable with cement and other suitable rig-lessly deployable permanent abandonment materials, with various embodiments usable to clean bores and annuli of hazardous or benign debris that could potentially interfere with the placement of permanent impermeable barriers, e.g. cement, to further provide wettable surfaces for cement bonding, wherein portions of the well may be opened to dispose of hazardous material, such as LSA scale, during abandonment.
The most prevalent permanent barrier for well abandonment is a cement column of a depth sufficient to ensure good quality and bonding of the cement to completion equipment. The surface of the completion equipment must be both wettable and accessible during cement slurry placement. If equipment, such as completion equipment or casing, is left within the strata bore, the cement must also be placed on both sides, embedding the equipment or casing in bonded cement, since over time the metal equipment may corrode if poor cement bonding or the lack of cement bonding exposes corrodible equipment to subterranean fluids, subsequently providing a leak path. Cemented casing is not considered a permanent barrier to lateral flow, into or out of the wellbore, unless the inner and outer diameters of the casing and contained conduits are sealed with good quality cement, which is bonded to the casing. It is noted that fluids may migrate through poor quality cement or axially along the casing's inner or outer surface through micro annuli if poor bonding exists, to eventually corrode the casing when an incomplete localised cement sheath is present in the internal bore or annulus.
Various other embodiments of the present invention are usable to provide both space and offset of eccentric conduits to allow cleaning of downhole completion equipment and casings, both fluidly and mechanically, to provide cleaner spaces and wettable surfaces and to provide sufficient good quality cement bonding, thus preventing axial or lateral pressurized fluid flow.
Because the lifespan of an installed permanent well barrier can be measured in geologic time, i.e. over millions of years, and as nature abhors a vacuum, well barriers must also be designed to resist the re-pressurization of a depleted reservoir as it seeks to return to its original state over time. In many subsurface reservoirs, this requires placing barriers at specific depths to replace the original cap rock holding the pressurized subterranean fluids, before it was penetrated by a well. The lack of foresight in the original well design is often a primary reason for using drilling specification rigs to abandon wells, because completion equipment, e.g. production packers, are incorrectly placed for conventional rig-less abandonment and/or marginal production enhancement when such packers either fail to isolate or prevent access to isolated marginal producible formations.
Other embodiments of the present invention are usable to access all surrounding annuli, replacing and/or bypassing production packer isolation of an annulus, while still other embodiments are usable to access isolated marginal producible formations or access injectable strata formations for disposal of hazardous materials, during suspension and/or side-tracking of a well and placement of annuli isolations and to access conduits to delay or perform final abandonment of a well, to potentially reduce the net present cost of abandonment.
Preventing exposure of the environment and personnel to hazardous materials, e.g., hydrocarbons from marginal producible formations, brines, H2S occurring naturally or as a result of water injection, and/or LSA scale or NORM, with a reasonable probability of success both during well operations and for the indefinite period thereafter, requires redundancy, i.e. a plurality of tested barriers that can be verified. The integrity of a well is generally measured both during operations and abandonment, by the existence of at least two verified barriers.
Various embodiments of the present invention are usable to provide supported annuli cement placement for a plurality of annuli barriers that are verifiable with the conventional methods of logging and tagging, but which are unavailable to conventional rig-less applications due to their inability to selectively access annuli or conduct pressure testing through the annuli access passageways, wherein the present invention is usable to access all annuli to abandon all or part of a subterranean well.
Well operators face a series of challenges at each stage of a well's lifecycle as they seek to balance the need to maximise economic recovery and reduce the net present value of an abandonment liability to meet their obligations for safe and environmentally sensitive operations and abandonment. When wells lose structural integrity, which may be defined as an apparent present or probable future loss of pressure or fluid bearing capacity and/or general inoperability, all or portions of a well may be shut-in for maintenance or suspension until final abandonment or may require immediate plugging and abandonment, potentially leaving reserves within the strata that cannot justify the cost of intervention or a new well.
Some of the more frequently reported structural integrity problems are a lack of centralization leading to conduit erosion from thermal cycled movement, corrosion within the well conduit system; e.g., from biological organisms or H2S forming leaks through or destroying conduits or equipment and/or valve failures associated with subsurface safety valves, gas lift valves, annuli valves and other such equipment. Other common issues include unexplained annulus pressure, connector failures, scale, wear of casings from drilling operations, wellhead growth or shrinkage and Xmas or valve tree malfunctions or leaks at surface or subsea. Such issues comprise areas where operators are able to, or chose to, test and there are others (such as the internals of a conductor) which they cannot, or do not test, and which may represent a serious risk to economic viability and the environment. Problems within various portions of a well, in particular the annuli, cannot be conventionally accessed without significant intervention or breaking of well barriers, e.g., with a drilling rig, and thus, are a significant cost and safety risk to operators that are unsuitable for conventional rig-less operations mitigation.
A primary advantage of using drilling specification rigs for well intervention is the removal of conduits and access to annuli during well intervention and abandonment, wherein the ability to access and determine the condition of the annuli casing and primary cement behind the production conduit or tubing is used to make key decisions regarding the future production and/or abandonment. If well casings are corroded or lack an outer cement sheath, remedial action, e.g., casing milling, may be undertaken to provide a permanent barrier. Conversely, the problem may be exacerbated by conventional rig-less well abandonment when blind decisions are made without cement logging access to annuli and attempts to place cement fail, thereby placing another barrier over potentially serious and worsening well integrity issues, which can represent a significant future challenge, both technically and economically, even for a drilling rig.
Various embodiments of the present invention are usable to gather information that conventional rig-less operations cannot, by providing access and/or space for both measurement devices and sealing materials. Once such information is gathered, still other embodiments are usable to rig-lessly place barriers, and/or mill or shred conduits and casings to expose and bridge across hard impermeable strata or cap rock formations for placement of permanent barriers without imbedded equipment to ensure structural integrity.
In general, age is believed to be the primary cause of structural well integrity problems. The combination of erosion, corrosion and general fatigue failures associated with prolonged field life, particularly within wells exceeding their design lives, together with the poor design, installation and integrity assurance and maintenance standards, associated with the aging well stock, is generally responsible for increased frequency of problems over time. These problems can be further exacerbated by, e.g., increasing levels of water cut, production stimulation, and gas lift later in field life.
However, the prevalent conventional consensus is that although age is undoubtedly a significant issue, if it is managed correctly, it should not be a cause of structural integrity problems that may cause premature cessation of production. Additionally, fully depleting producing zones through further production prior to abandonment provides an environment of subterranean pressure depletion that is better suited for placing permanent barriers, by lowering the propensity of lighter fluids to enter, e.g., cement during placement.
A need exists for delaying abandonment with low cost rig-less operations for placement of well barrier elements to increase the return on invested capital, for both substantially hydrocarbon and substantially water wells, through rig-less side-tracking, for marginal production enhancement, suspending and/or abandoning portions of a well, to re-establish or prolong well structural integrity for aging production and storage well assets; and thus, prevent pollution of subterranean horizons, such as water tables or surface and ocean environments.
A need exists for small operating foot-print rig-less well barrier element placement operations that can be usable to control cost and/or perform operations in a limited space, e.g. electric line or slickline operations, on normally unmanned platforms, from boats over subsea wells or in environmentally sensitive area, e.g. permafrost areas, where a hostile environment and environmental impact are concerns. A related need also exists for working within a closed pressure controlled envelope to prevent exposing both operating personnel and the environment to the risk of losing control of subterranean pressures, particularly if a well intervention kill weight fluid column is lost to, e.g., subterranean fractures.
A need exists for avoiding the high cost of drilling rigs with a rig-less system capable of suspending, side-tracking and/or abandoning onshore and offshore, surface and subsea, substantially hydrocarbon and substantially water wells using and/or complying with the published conventional best practices for placement of industry acceptable permanent abandonment well barrier elements.
A need exists for preventing risks and removing the cost of protecting personnel and the environment from well equipment contaminated with radioactive materials and scale by rig-lessly placing abandonment barriers and leaving equipment downhole. A further need exists to rig-lessly side-track or fracture portions of a well to dispose of hazardous materials resulting from circulation of the wells fluid column during suspension, sidetracking and abandonment operations.
A need exists for rig-lessly accessing annuli to measure whether acceptable sealing cementation exists behind casing and to rig-lessly mill the casing and place cement if acceptable cementation does not exist. A further need exists to verify the placement of well barrier elements during rig-less operation to ensure the successful settable material bonding and sealing of a well's passageways has occurred or whether further remedial work is required.
A need exists for rig-lessly accessing annuli presently inaccessible with minimal foot-print conventional slickline rig-less operations, including bypassing annulus blockages, created, e.g., by production packers, during placement of permanent well barrier elements within selected portions of a well across from cap rock and other impermeable formations needed to isolate subterranean pressures over geologic time.
A need exists for a plurality of permanent well barriers that are verifiable through selectively accessed annuli passageways with rig-less operations usable with conventional logging tools to maintain the structural integrity of a well prior to final abandonment, which also provide access for placing permanent barriers to ensure structural integrity of the strata bore hole thereafter.
A need exists for marginal production enhancement usable to offset operating costs until final abandonment occurs, including rig-lessly providing well integrity while waiting until an abandonment campaign across a plurality of wells can be used to further reduce costs.
A need exists to reduce the abandonment liability for operators while meeting their obligations of structural well integrity for safe and environmentally sensitive well operations, suspension and abandonment in an economic manner that is consistent with providing more capital for exploration of new reserves to meet our world's growing demand for hydrocarbons by minimising the cost of operations, suspension and abandonment with lower cost rig-less suspension, side-tracking and abandonment technologies.
Finally, verifiable rig-less well abandonments are needed to facilitate a market where the reduction of well abandonment liability allows larger operating overhead companies to sell marginal well assets to smaller lower overhead operating companies, i.e. by lowering the risk of a residual abandonment liability, to prevent marginal recoverable reserves from being left within the strata because higher operating overhead requirements made such recoverable reserves uneconomic.
Various aspects of the present invention address these needs.